70%

来源: 于 2010-04-27 10:03:54 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

Assume A, B, C, D, E, F, G born in April
Same day with A: AB AC AD AE AF AG, 1/30 chance for each combination
Similarly:
BC BD BE BF BG 1/30
.
.
.
FG 1/30
Total: 21/30 = 70%